Understanding Materials: Properties, Metals, and Alloys
Materials and Classification
A material is any substance used for the construction of an object. Raw materials are resources obtained from nature and used in a post-production process. A raw material may not always be a material in the direct sense, for example, oil.
Evolution of Materials
Each new stage of technological development has led to the incorporation of new materials, some of which become so important that they designate an era, such as the Stone Age, the Bronze Age, and the Iron Age. Currently, humans have synthesized materials that do not exist in nature, such as plastics.
Material Features
Materials are ranked according to different criteria:
- Electromagnetic: Conductivity, electricity, and relationship with magnetic fields.
- Thermal: Refractory characteristics.
- Chemical: Resistance to acids, describing how a material reacts with other substances.
- Optical: Transparency, referring to interaction with light.
Mechanical properties are especially important in the manufacture of objects. The main ones are:
- Hardness: Resistance of a material to being drilled or scratched.
- Tenacity: The ability of a material to not warp or break when a force is applied.
- Plasticity: The ability of a material to deform under the action of a force and hold the new shape.
- Elasticity: The capacity of a material to recover its original form once the force causing deformation ceases.
- Ductility: The capacity of a material to undergo large deformations without breaking.
- Malleability: The capacity of a material to suffer plastic deformation without rupture.
Metals and Alloys
Metals and alloys are materials of mineral origin composed of one or more metallic elements.
- If the material is formed by one chemical element, it is a pure metal.
- If the material is formed by more than one chemical element, it is an alloy.
Pure Metals
Pure metals are rarely plentiful and are usually found in nature as part of minerals, which are often difficult to refine.
- They are very hard.
- They can be worked through foundry processes, allowing their configuration in several ways: rods, plates, pipes, etc.
- They are good conductors of heat and electricity.
- They have great mechanical strength, allowing the formation of high-stress structures.
- They can be easily recycled.
Their main drawback is that they easily oxidize when exposed to the atmosphere, causing the formation of oxides that make them lose their metallic properties.
Copper
- It is believed to be the first metal used by man in its pure form.
- It is abundant and easy to obtain, found in almost pure state and in minerals from which it is easy to separate.
- It is a very good electrical conductor.
- It is very flexible.
- It is easy to work with.
- It is malleable.
- It is relatively resistant to corrosion.
Iron
- It is the most used metal today.
- It is abundant.
- It has great resistance.
- It has great malleability.
- It has magnetic properties (it is used for magnets).
- It is easy to work with and agrees with welding foundry.
Its main drawback is that it corrodes easily with oxygen in atmospheric environments, especially with humidity and salinity. Therefore, it is protected with antioxidant coatings like paint. In most cases, alloys such as steel are preferred.